ANM 1.2: "configure device error: null" when generating a CSR

I have a problem with ANM 1.2. When I navigate to Config-> [chassis] -> ACE module -> [context] -> SSL -> Keys, select a key, click on "Generate CSR..." and confirm with "OK" , I get the following error:

"Failed to deploy config to device: Configure device error: null"

At the same time, the following message is written to /var/lib/anm/events/20080220/dev/main.20080220.dev.0.txt: